package basic_practice_1004;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		
		List<Long> breakfast=new ArrayList<Long>();
		List<Long> sum=new ArrayList<Long>();
		breakfast.add((long) 0);
		sum.add((long) 0);
		breakfast.add((long) 1);
		sum.add((long) 1);
		breakfast.add((long) 1);
		sum.add((long) 2);

		Scanner scanner=new Scanner(System.in);
		while(scanner.hasNext()) {
			int from=scanner.nextInt();
			int to=scanner.nextInt();
			
			while(to>=sum.size()-1) {
				addDay(breakfast,sum);
			}
			System.out.println(sum.get(to)-sum.get(from-1));
		}
		
		scanner.close();
	}
	
	static void addDay(List<Long> breakfast,List<Long> sum) {
		breakfast.add(breakfast.get(breakfast.size()-2)+breakfast.get(breakfast.size()-1));
		sum.add(sum.get(sum.size()-1)+breakfast.get(breakfast.size()-1));
	}
	
}
